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Practical aspects of the estimation of the time of ovulation and of insemination in the bitch
Author(s) -
WRIGHT PJ
Publication year - 1991
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1991.tb09830.x
Subject(s) - ovulation , insemination , artificial insemination , semen , sperm , andrology , reflex , pony , medicine , endocrinology , biology , pregnancy , hormone , genetics
SUMMARY The aims of this study were to assess the precision of the estimates of the time of ovulation derived by various methods, and to define the most appropriate methods for the determination of the optimal time for insemination of bitches with fresh semen (artificial insemination or natural mating), or with frozen‐thawed semen. In 11 Labrador bitches, ovulation was estimated (plasma LH surge + 48 h) to occur 9 to 20 d after the start of the cycle, 0 to + 4 d after the onset of positive postural reflexes (2 bitches showed no positive postural reflexes), ‐ 4 to + 7 d after reaching a vaginal cytological eosinophilic index (El) of 100%, over a range of 2.5 to 5.5 d based on plasma progesterone concentrations of 4 to 10 ng/ml, over a range of 2 to 3 or 4 d based on 2 indirect methods of estimating the time of the plasma LH surge from plasma progesterone concentrations. Assuming fertilisation occurs 2 to 3 d after ovulation, these findings indicate that for fresh semen (with an estimated lifespan of > 4 days) an appropriate procedure would be to inseminate/mate on the day after the onset of positive postural reflexes; then 3 days later. For bitches not showing positive postural reflexes, insemination should occur when the vaginal El = 90% and then each 3 d until day 1 of dioestrus (D1). For frozen‐thawed semen (with a lifespan of >24 h) insemination should occur 4 to 5 d after the plasma LH surge. Thus, 1 insemination is required after direct measurement of the plasma LH surge, or 3 inseminations at 24 h intervals based on the less precise indirect assessment of the time of the plasma LH surge derived from measurement of plasma progesterone concentrations.